The need for efficient and environmentally sound methods of waste disposal is ever more urgent. Landfills have been used extensively for waste disposal, since landfill usage typically requires only the collection and transport of the waste to the site. However, landfills require space, and that is something many countries have less and less of, particularly in and adjacent to urban areas, which areas generate the greatest volume of waste material. Landfills, if unsecure, are also not an environmentally friendly solution.
Waste organic materials may decompose and yield harmful products capable of contaminating the soil and ground water. Other organic wastes (such as vehicle tyres and plastic products) exhibit little or no decomposition in a landfill. At present, there are many landfills devoted exclusively to used vehicle tyres, some containing several million tyres each. Any fire in such tyre dumps are extremely difficult to extinguish, and emit huge amounts of pollution. It is therefore desirable to destroy the waste as opposed to merely storing it.
One known method of disposing organic waste is by gasification, which is a process whereby the waste is subjected to high temperature in a low oxygen environment to produce a synthesis gas. U.S. Pat. No. 4,025,532 to Meuser et al. and U.S. Pat. No. 5,085,738 to Harris et al. disclose apparatuses for continuous feed pyrolysis processes having an oxygen free atmosphere over a molten metal bath in which organic solids are thermally converted to hydrocarbon vapors, particulate matter and residual solids. However, both of these processes have been found to have too many operational problems to be commercially viable. The problems include difficulties with the separation and removal of particulate matter and residual solids and, referring particularly to the apparatus in U.S. Pat. No. 5,085,738, difficulties in maintaining an oxygen free atmosphere over the molten metal bath while continually feeding the organic solids therein.
Other known methods have other kinds of drawbacks, such as producing pollutants during the disposal process, not being able to process inorganic waste along with the organic fraction of the waste, or do not produce enough energy even to support the waste disposal process.
What is needed in the art is a method or system that is able to destroy waste in a safe and controlled environment, generate energy and produce useable fuel and recyclable by-products from the destruction of the waste.